A. Field of the Invention
The present invention relates broadly to systems for loading and unloading cargo containers with fluid-like or fluidizable cargos. The invention more particularly concerns a system wherein a self-installing, self-fitting liner is inflated within a cargo container, and a cargo is then charged into the liner. Special features include a transparent bulkhead to permit observation of the cargo and inflatable bags to improve recovery of cargo from the container.
B. Description of the Related Art
Conventional cargo containers are routinely used to transport flowable bulk cargo such as pelletized plastic, grain, pulverized materials and the like. These containers may be transported on truck beds or rail cars or individually shipped in container ships or on barges. They may also be used to store materials at sites to which they are delivered. Typically, these containers conform to standard specifications regulated by the American Standard Association or similar international associations.
Where flowable bulk cargo, including liquid and semi-liquid material, is to be transported in a conventional cargo container, modern practice typically dictates protecting both the cargo and container with a flexible liner. The dimensions of the liner roughly correspond to the internal dimensions of the container. Containment of the cargo inside such a liner provides many advantages including protection of the container from contaminating cargo, protection of the cargo from contamination, exclusion of dust and moisture from the cargo, and similar functions. Many different styles of liners have been designed to accommodate the various functions required.
The installation, loading and unloading of bulk cargo from liners within containers has been a fertile area for invention. Many liners, for example, require the use of a bulkhead positioned between the liner and the unloading portal. This portal, in most cases, embodies the rear doors of the container. In a typical transportation operation, the load within the liner is transferred to the bulkhead which may serve as a load-bearing retaining wall or may transfer the load to another load-bearing retaining wall such as the doors of the container. As noted above, such doors are normally at the rear end of a container, and they will be referred as the "rear doors" herein.
During a typical unloading process, bulk cargo is removed from a container by first allowing gravity flow, establishing a line of repose of the cargo within the container and then tilting the entire container and achieving further gravity flow of the bulk cargo out of the liner through a portal in the bulkhead positioned near the rear doors of the container. Alternatively, low pressure suction devices may be used to eliminate the requirement for tilting. Unloading with suction, however, requires special equipment. Although it is possible to remove a large percentage of the cargo from a container using the above conventional techniques, typically there is a residual amount of the cargo retained in the corners nearest the unloading portal.
Several bulk cargo handling systems already have been designed which attempt to overcome the above problems. For instance, numerous patents have been issued for bulkheads, liners, and unloading assistance devices. Some patents describe bulk cargo handling systems which include all three such features--i.e., bulkheads, liners, and unloading assistance devices.